Don't install pep8 from packages

We have migrated to flake8 and most distros don't have the version of
pep8 that flake8 (and hacking) use.  Instead of installing pep8 from
packages it should be installed from pip

Change-Id: I86e4f8316f3cdc27303bfd039a78c0d6202ce321
Merge "Don't install pep8 from packages"